In the Program Project we will make use of various comprehensive global gene expression methodologies described in projects 1 and 2, with the final goal of generating a molecular signature of lymph node-negative (ANN) breast carcinomas. The most important functions of the Pathology Core will be to obtain, distribute, and archive tumor samples and coordinate the retrieval of patient and clinical information related to each sample. The purpose of the Pathology Core is to provide high-quality well-characterized (clinically and histopathologically) ANN breast carcinoma samples for the global gene expression studies described in this application. We will also perform immunohistochemical staining for a basic battery of markers in every specimen. As antibodies for each protein of interest identified in Projects 1 and 2 become available, they will be added to this battery. The Specific Goals of the Pathology Core are: 1. To select the patient population for the Program. 2. To provide and coordinate professional and technical services for proper handling and processing of tissue samples and to distribute well- characterized specimens to Project investigators. 3. To maintain a frozen tissue bank of all Project-related specimens. 4. To perform histopathologic review of each sample. 5. To perform Laser microdissection review of each sample 6. To maintain a computerized database tracking system of clinical and pathologic information for each specimen. Complete clinical information will be obtained from the Breast Cancer Management Database (BCMS). 7. To maintain patient confidentiality by establishing an internal Program identifier for each sample. This identifier will be linked to the Patient registration number by a second database kept by the Core under password protection. This activity will be performed in coordination with the Database Management Core B. 8. To evaluate immunohistochemical markers.